diff --git a/rastervision_core/rastervision/core/data/utils/misc.py b/rastervision_core/rastervision/core/data/utils/misc.py
index a26328d32..914d18633 100644
--- a/rastervision_core/rastervision/core/data/utils/misc.py
+++ b/rastervision_core/rastervision/core/data/utils/misc.py
@@ -13,8 +13,8 @@
 log = logging.getLogger(__name__)
 
 
-def color_to_triple(
-        color: str | Sequence | None = None) -> tuple[int, int, int]:
+def color_to_triple(color: str | Sequence | None = None
+                    ) -> list[str] | tuple[int, int, int]:
     """Given a PIL ImageColor string, return a triple of integers
     representing the red, green, and blue values.
 
diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/learner.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/learner.py
index f9762f83b..ce370a92c 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/learner.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/learner.py
@@ -1181,8 +1181,9 @@ def build_dataset(self,
         ds = self.cfg.data.build_dataset(split=split, tmp_dir=self.tmp_dir)
         return ds
 
-    def build_dataloaders(self, distributed: bool | None = None
-                          ) -> tuple[DataLoader, DataLoader, DataLoader]:
+    def build_dataloaders(
+            self, distributed: bool | None = None
+    ) -> tuple[DataLoader, DataLoader, DataLoader | None]:
         """Build DataLoaders for train, validation, and test splits."""
         if distributed is None:
             distributed = self.distributed
diff --git a/rastervision_pytorch_learner/rastervision/pytorch_learner/learner_config.py b/rastervision_pytorch_learner/rastervision/pytorch_learner/learner_config.py
index c9326ad1e..1ed445586 100644
--- a/rastervision_pytorch_learner/rastervision/pytorch_learner/learner_config.py
+++ b/rastervision_pytorch_learner/rastervision/pytorch_learner/learner_config.py
@@ -680,7 +680,7 @@ def num_classes(self):
 
     @field_validator('augmentors')
     @classmethod
-    def validate_augmentors(cls, v: list[str]) -> str:
+    def validate_augmentors(cls, v: list[str]) -> list[str]:
         for aug_name in v:
             if aug_name not in augmentors:
                 raise ConfigError(f'Unsupported augmentor "{aug_name}"')
@@ -862,8 +862,7 @@ def validate_group_uris(self) -> Self:
 
     def _build_dataset(self,
                        dirs: Iterable[str],
-                       tf: A.BasicTransform | None = None
-                       ) -> tuple[Dataset, Dataset, Dataset]:
+                       tf: A.BasicTransform | None = None) -> Dataset:
         """Make datasets for a single split.
 
         Args:
@@ -1224,7 +1223,7 @@ def _build_dataset(self,
                        split: Literal['train', 'valid', 'test'],
                        tf: A.BasicTransform | None = None,
                        tmp_dir: str | None = None,
-                       **kwargs) -> tuple[Dataset, Dataset, Dataset]:
+                       **kwargs) -> Dataset:
         """Make training, validation, and test datasets.
 
         Args: